This project is designed to cultivate directly in cell culture a variety of human rotavirus strains from diverse geographical areas and populations in order to define antigenic differences and to identify and develop potential vaccine candidates. In the evaluation of virus strains we have employed a variety of cell types including MA104 and primary African green monkey kidney (AGMK) cells. The technique for cultivation used in this study was described recently by Japanese investigators. Over 30 strains of human rotaviruses have been cultivated in MA104 cells and 10 of these were reisolated in AGMK cells. Four distinct serotypes of human rotavirus have been identified and compared with each other. The serotypic characterization of the reassortant human-bovine rotaviruses previously studied in our laboratory and these direct isolates was in agreement. It is of particular interest that a rhesus, canine, and feline rotavirus are all similar if not identical to one of the human rotavirus serotypes. Finally, it is important to note that several potential candidate vaccine strains of different serotypes have been grown in a cell type suitable for vaccine production, and these now can be evaluated further for safety and efficacy.